Integration of metabolism Flashcards
What can the brain NOT metabolise?
Fatty acids
What can partially substitute for glucose in the brain?
Ketone bodies
At what concentration is blood glucose conc. in the liver kept at?
4 - 5.5 mM
What energy sources do muscles and the heart use?
carbohydrate and fatty acid metabolism
What can pyruvate and other TCA cycle intermediates be a source of?
Amino acids
Backbone of this molecule can be used to make nucleotides
What can be used as a source of nucleotide production?
Glucose-6-phosphate via pentose phosphate pathway.
Generates bulk NADH needed for anabolic pathways
What levels of blood glucose leads to a hypoglycaemia coma?
Levels below 30mM
What short term things does the body do to avoid hypoglycaemia?
Break down glycogen stores in liver
Release free fatty acids from adipose tissues
Convert acetyl CoA into ketone bodies via liver
These effects only last 12-18 hours so gluconeogenesis pathway used to make more glucose
What is the aim of gluconeogenesis?
Avoid hypoglycaemia by producing glucose from pyruvate/ oxaloacetate
Pyruvate can be converted to oxaloacetate by pyruvate carboxylase or converted to acetyl CoA which enters TCA cycle
Whats distinct about reactions that are catalysed by kinases in glycolysis?
They’re reversible so phosphatases used to do the reverse of the reaction
What happens to oxaloacetate?
Converted by phosphenolpyruvate carboxykinase to phosphenolpyruvate then converted to…
Fructose- 1,6,- bisphosphate converted to fructose 6-phosphate by fructose-1,6,- bisphosphotase
Glucose-6-phosphate converted to glucose by glucose 6 phosphatase
How can lactate be used to regenerate pyruvate?
Lactate can be taken up by the liver and utilised to regenerate pyruvate by lactate dehydrogenase (LDH) also known as the cori cycle
What non-carbohydrate precursors enter gluconeogenesis?
Lactate, amino acids, glycerol
Where are amino acids derived from?
Amino acids can be derived from diet or during times of starvation
What happens to triglycerides in gluconeogenesis?
Triglyceride hydrolysis yields fatty acids and glycerol.
glycerol backbone generates dihydroxyacetone phosphate (DHAP)